Creasing cellulosic fiber strips

ABSTRACT

A longitudinal groove is formed in a surface of an advancing cellulosic fiber strip such as &#39;&#39;&#39;&#39;wallboard tape,&#39;&#39;&#39;&#39; and the strip is caused to bend along the length of the groove and fold upon itself.

United States Patent Hollier, Jr.

14 1 Apr.'29, 1975 CREASING CELLULOSIC FIBER STRIPS Joseph H. Hollier.Jr.. Peurcy. Ark.

Assignee: Sutco. lnc.. Hot Springs. Ark.

Filed: May ll. I973 Appl. No.: 359.218

Inventor:

U.S. Cl 93/84 R: 93/1 R: 93/20 1m. Cl 1531b 1/36 Field of Search 93/84R. 1 R. 1 F. 21)

References Cited UNITED STATES PATENTS 11/1936 Milletl 93/84 R X2.270.721 1/1942 Weslphul 93/84 R X 2.385.646 9/1945 Poppc 11 93/20 X2.929.303 3/1961) Armstrong 93/114 R 3.164.111) 1/1965 Wilkic L2! :1193/84 R 3.165.311) 1/1965 Peterson M 93/84 R Primary Examiner-Roy LakeAazs'l'xumr kirurm'rrcr-James F. Cnun Armrncy, Agent. or Firm-Gc0rgc F.Hclfrich 1571 ABSTRACT A longitudinal gmuve is formed in a surface 01 anadvancing cellulosic fiber strip such as wallbonrd tape." and the stripis caused to bend along the length of the groove and fold upon itself.

1 Claim. 2 Drawing Figures CREASING CELLULOSIC FIBER STRIPS BACKGROUNDOF THE INVENTION l. Field of the Invention This invention relates to aprocess and device for creasing cellulosic fiber strips. It relatesparticularly to a process and device for creasing paper strips which areadvantageously utilized in covering joints between abutting wallboardedges.

2. Prior Art In the fabrication of cellulosic fiber strips. it is oftennecessary that the strips be creased as a prerequisite to theirutilization in certain applications. For example. in the production ofpaper strips for employment in the covering and reinforcing of coplanarand corner joints formed by abutting wallboard edges (such strips beinggenerally referred to as wallboard tape") it has been found necessary tocrease the wallboard tape along its longitudinal axis. so that it may besubsequently effectively used by workmen in application to all joints.especially the corner joints. (If the tape is creased by the workman onthe job without the aid of special tools. difficulty is experienced infolding the tape along a line substantially equivalent to thelongitudinal axis of the tape. and the so'creased tape does not readilyconform to and completely overlie the joints. especially the cornerjoints. Although the employment of certain special creasing tools byworkmen on the job docs facilitate the obtainment of a straightlongitudinal fold in the tape. such adds to the overall cost of thecompleted job. as a result of increased time and tool charges.)

Accordingly. a number of production expedients have been devised forcreasing cellulosic fiber strips. especially those employed as wallboardtape. The formation of a simple indentation or groove in the strip hasbeen found to be ineffective of itself. unless the groove is deep enoughto significantly weaken the strip. Furthermore, a simple folding of thestrip has been found to be unsatisfactory, because the center of thestrip is rendered thicker thereby. resulting in difficulties in windingon a roll. An example typifying recent expedients is the method ofPeterson. et al. US. Pat. No. 3.086.328. Notwithstanding the efficacy ofthis and similar expedients. they are found wanting. as a closeexamination of their characteristics reveals. For example. Petersonstechnique requires that the advancing tape be first moistened centrallyon both sides with water. followed by a complete soaking thereof. atwhich time the creasing action is accomplished. Peterson's tape isfinally dried and ironed under tension to a perfectly flat condition.whence it is wound for subsequent utilization. Complicated proceduressuch this require increased production time and careful productioncontrol. thereby adding substantially to the cost of the product-whichis unacceptable in view of today's requirements for improved products.as well as enhanced efficiency and reduced costs in manufacturingoperations.

SUMMARY OF THE INVENTION Accordingly. it is the primary ofject of thisinvention to provide a simple and economical. yet highly efficientprocess and device for the creasing of cellulosic fiber strips,especially those to be employed as wallboard tape.

In accordance with the present invention. this object and theseadvantages are achieved. and the disadvantagcs of the prior art areobviated by providing a continuous process comprising forming alongitudinal groove in a surface of an advancing cellulosic strip andthen causing the strip to bend along the length of the groove and foldupon itself.

An apparatus which is especially advantageously employed in thiscontinuous process comprises (a) means for forming a longitudinal groovein a surface of the advancing strip. and (b) means for causing the stripto bend along the length of the groove and fold upon itself. such meansadvantageously comprising an elongated. rigid sheet the extremelongitudinal edges thereof being bent inwardly over the upper surfacethereof to form a channel for guiding the course of the advancingcellulosic strip. the channel having an en trance end and an exit end.the body of the sheet being bent along the longitudinal axis thereof.the degree of flexure increasing from substantially zero at the entranceend of the channel to an infoldment at the exit end thereof.

Furthermore. it has been found of especial advantage if the apparatusadditionally comprises adjust means positioned downstream of the exitend of the channel for adjusting the proximity of the halves oftheplicature produced in the advancing cellulosic fiber strip.

BRIEF DESCRIPTION OF THE DRAWING For a more complete understanding ofthe present invention. reference should be made to the detaileddescription of the preferred embodiments thereof. which is set forthbelow. which description should be read together with the accompanyingdrawing. wherein:

FIG. 1 is a schematic side elevation illustrating a preferred embodimentof the process and depicting a prcferred embodiment of an apparatusaccording to the present invention; and

FIG. 2 is a perspective view of a part of the apparatus depicted in FIG.I.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawing.there is shown a continuous cellulosic fiber strip (11) being unwoundfrom supply roll (I2) and guided by idler roll (13) so that it passesacross the surface of idler roll (14). Cellulosic fiber strip (II) isadvantageously a wallboard tape. which is conveniently prepared fromwood pulp paper. and has a substantial portion of its cellulosic fibersextending in a direction transverse to the longitudinal axis of thetape. The tape may be provided with a multiplicity of smallperforations. if desired. Idler roll (14) is a broad roll. i.e.. it hassubstantial length in the direction of its axis. The surface of idlerroll (14) may be constructed form resilient material such as plastic orhard rubber. if desired. but this is not essential. Urged into contactwith the upper surface of strip (11) as it passes over the surface ofidler roll (I4) is idler roll (15). which is a narrow" roll. i.e.. ithas very little length in the direction of its axis. The surface ofidler roll (I5) is advantageously constructed of hard. wearresistantmaterial such as stainless steel; and idler roll (I5) is convenientlyurged into contact with strip (II) along its longitudinal axis as itpasses over the surface of roll (14). by means of spring (I6) or otherequivalent means. Hereby. a small groove (21) is formed in one surfaceof strip (I I) along its longitudinal axis. the width of the groovebeing equivalent to the axial length of idler roll For a strip (ll)having a width of about 2 inches, acceptable widths of longitudinalgroove (2|) have been found to be between about 0.005 and 0.060 inches.The depth of groove (Zl may vary between limits if desired; however. itshould be between about 15 and 50 percent of the thickness of strip (llThe depth may be conveniently varied by changing the tension on spring16). If the surface of idler roll (14) is constructed from resilientmaterial. strip (11) exiting from rolls l4) and ([5) will have alongitudinal groove in one surface and a convex longitudinalprotuberance in the other. This. although perfectly acceptable and evenadvantageous under certain conditions. is not essential.

After longitudinal groove (2i has been formed therein, strip (II) isadvanced into the entrance of folding device (17) which is an elongatedrigid sheet having its extreme longitudinal edges bent inwardly over itsupper surface to form a channel for guiding the course of travelingstrip (ll). (The construction and function of folding device (l7) arebest comprehended by referring to FIG. 2.) The main body of the sheetcomprising folding device (I7) is permanently bent along itslongitudinal axis. the degree of flexure or bend increasing fromsubstantially zero at the entrance end of the channel to a substantialinfoldment at the exit end of the channel. i.e.. the longitudinal endsof the sheet are bent back upon themselves at the exit end of thechannel. As it advances through folding device (l7). strip (11) is bentalong groove (21) until a fold is produced in strip (ll) at the point ofits exit from folding device (17). The tightness of the fold. i.e., theactual proximity of the halves of the plicature produced in strip (ll).is advantageously regulated by adjust means (23). which is locateddownstream of the exit end of the channel of folding device (17) bymeans of positioning bolt (22). The closeness of rods ([8), andconsequently the proximity of the halves of the fold in strip (II). isregulated by loosening nuts (not shown) at the bottom of rods (18) andmoving rods 18) either toward or away from each other in an elongatedslot (not shown) in base plate (24).

After it passes through adjust means (23). strip (11 is allowed toassume its original, flat, unfolded configuration. and is wound uponroll (20) after passing over idler 19). At the position of groove (21) apermanent crease has been produced in strip (II), and strip (ll) as awallboard tape is eminently suitable for application to both coplanarand corner wallboard joints.

What is claimed is:

1. An apparatus for producing a crease in an advancing cellulosic fiberstrip, the apparatus comprising:

a. means for forming a longitudinal groove in a surface of the strip sothat the depth of the groove is between about 15 and 50 percent of thethickness of the strip;

b. means for causing the strip to bend along the length of the grooveand fold upon itself;

c. adjust means positioned downstream of the folding means for adjustingthe proximity of the halves of the plicature produced in the advancingcellulosic fiber strip; and

d. means for allowing the cellulosic fiber strip to assume its original,flat, unfolded configuration and winding said strip in suchconfiguration for subsequent utilization.

a: k a a

1. An apparatus for producing a crease in an advancing cellulosic fiberstrip, the apparatus comprising: a. means for forming a longitudinalgroove in a surface of the strip so that the depth of the groove isbetween about 15 and 50 percent of the thickness of the strip; b. meansfor causing the strip to bend along the length of the groove and foldupon itself; c. adjust means positioned downstream of the folding meansfor adjusting the proximity of the halves of the plicature produced inthe advancing cellulosic fiber strip; and d. means for allowing thecellulosic fiber strip to assume its original, flat, unfoldedconfiguration and winding said strip in such configuration forsubsequent utilization.